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Unified Diff: native_client_sdk/doc_generated/reference/pnacl-c-cpp-language-support.html

Issue 419803005: PNaCl documentation: clarify vector alignment, and update navigation (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Created 6 years, 5 months ago
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Index: native_client_sdk/doc_generated/reference/pnacl-c-cpp-language-support.html
diff --git a/native_client_sdk/doc_generated/reference/pnacl-c-cpp-language-support.html b/native_client_sdk/doc_generated/reference/pnacl-c-cpp-language-support.html
index 7ee087ee66f1a051c876608b398b8645fba8579a..6d7d610ce3787f3bc1d53b9c884574e19987860a 100644
--- a/native_client_sdk/doc_generated/reference/pnacl-c-cpp-language-support.html
+++ b/native_client_sdk/doc_generated/reference/pnacl-c-cpp-language-support.html
@@ -195,9 +195,9 @@ very hardware-specific. Portable Native Client offers a portable version
of SIMD vector datatypes and operations which map well to modern
architectures and offer performance which matches or approaches
hardware-specific uses.</p>
-<p>SIMD vector support was added to Portable Native Client for version 37
-of Chrome and more features, including performance enhancements, are
-expected to be added in subsequent releases.</p>
+<p>SIMD vector support was added to Portable Native Client for version 37 of Chrome
+and more features, including performance enhancements, have been added in
+subsequent releases.</p>
<section id="hand-coding-vector-extensions">
<h3 id="hand-coding-vector-extensions">Hand-Coding Vector Extensions</h3>
<p>The initial vector support in Portable Native Client adds <a class="reference external" href="http://clang.llvm.org/docs/LanguageExtensions.html#vectors-and-extended-vectors">LLVM vectors</a>
@@ -225,8 +225,10 @@ v4s snip(v4s in) {
return ret;
}
</pre>
-<p>Vector datatypes are currently expected to be 128-bit wide with one of
-the following element types:</p>
+<p>Vector datatypes are currently expected to be 128-bit wide with one of the
+following element types, and they&#8217;re expected to be alignment to the underlying
+element&#8217;s bit width (loads and store will otherwise be broken up into scalar
+accesses to prevent faults):</p>
<table border="1" class="docutils">
<colgroup>
</colgroup>
@@ -234,36 +236,44 @@ the following element types:</p>
<tr class="row-odd"><th class="head">Type</th>
<th class="head">Num Elements</th>
<th class="head">Vector Bit Width</th>
+<th class="head">Expected Bit Alignment</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td><code>uint8_t</code></td>
<td>16</td>
<td>128</td>
+<td>8</td>
</tr>
<tr class="row-odd"><td><code>int8_t</code></td>
<td>16</td>
<td>128</td>
+<td>8</td>
</tr>
<tr class="row-even"><td><code>uint16_t</code></td>
<td>8</td>
<td>128</td>
+<td>16</td>
</tr>
<tr class="row-odd"><td><code>int16_t</code></td>
<td>8</td>
<td>128</td>
+<td>16</td>
</tr>
<tr class="row-even"><td><code>uint32_t</code></td>
<td>4</td>
<td>128</td>
+<td>32</td>
</tr>
<tr class="row-odd"><td><code>int32_t</code></td>
<td>4</td>
<td>128</td>
+<td>32</td>
</tr>
<tr class="row-even"><td><code>float</code></td>
<td>4</td>
<td>128</td>
+<td>32</td>
</tr>
</tbody>
</table>

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